Table 2.

Effect of high-dose intravenous vitamin C (IVC) on pain severity in cancer patients.

Study Type	Characteristics of Study Participants	Intervention	Outcome	References
Prospective	39 terminal cancer patients	10 g IVC twice with a 3-day interval in the first week, followed by oral intake of 4 g daily for one week	Reduced intensity of pain after IVC treatment	Yeom et al. [120]
Prospective	60 patients with newly diagnosed cancer, anti-cancer therapy administered in 34 patients	4 weeks of IVC therapy, median single dose 50 g (range 25–100 g)	Reduced intensity of pain after IVC treatment	Takahashi et al. [102]
Prospective	17 patients with advanced solid tumors refractory to standard therapy	IVC for 4 consecutive days a week for 4 weeks, starting at 30 g/m2, increased until a maximum tolerated dose (110 g/m2)	Reduced intensity of pain during IVC with complete pain relief after 4 weeks of IVC therapy	Stephenson et al. [28]
Controlled retrospective	39 patients with bone metastases, radiotherapy-resistant (n = 15 on chemotherapy; n = 15 on IVC therapy; n = 9 controls)	IVC group: 2.5 g IVC during pain	Median 50% reduction in pain intensity in IVC group	Günes-Bayir et al. [123]
Uncontrolled retrospective	11 cancer patients with bone metastases, unresponsive to standard cancer treatment	IVC 2.5 g once weekly for 3–10 weeks	Mean 55% reduction in pain intensity	Kiziltan et al. [138]
Case study	A female aged 53 with breast carcinoma with visceral and skeletal metastases, after mastectomy, radiotherapy, and hormonotherapy, terminal state with severe pain requiring opioids	5 g IVC for 7 days, followed by 8 g daily for 70 days orally (total 595 g)	Complete relief from bone pain Reduced need for opioids	Cameron and Campbell [7]
	A male aged 44 with poorly differentiated transitional cell cancer of bladder with bone metastases, intense pain inadequately controlled by opioids	10 g IVC for 10 days, followed by 10 g daily for 24 days orally (total 340 g)	Complete relief from bone pain No further need for opioids	Cameron and Campbell [7]
	A female 49 with disseminated carcinoma of unknown origin, innumerable osteolytic bone metastases, severe bone pain	10 g IVC for 7 days, followed by 10 g daily for 27 days orally (total 340 g)	Complete relief from bone pain	Cameron and Campbell [7]
	A male aged 49 with large malignant tumor of right temporal lobe, unknown histology, intolerable headache	10 g IVC for 11 days, followed by 10 g daily for 2 days orally (total 360 g)	Significant relief from headache	Cameron and Campbell [7]
Case study	A female aged 45 with recurrent breast cancer	50 g IVC twice a week for 4 weeks	Reduction in pain intensity	Carr et al. [121]
Case study	A male aged 81 with recurrent pulmonary angiosarcoma	30 g IVC daily for 1 week	Reduction in pain intensity	Carr et al. [122]